Abstract:The electrodeposition behaviors of nickel on glassy carbon (GC) and carbon steel (CS) electrodes were investigated in the 14.3%-85.7% (mole fraction) betaine·HCl-ethylene glycol (EG) ionic liquid using cyclic voltammetry and chronoamperometry. The results indicated that the reduction of Ni(II) on CS electrode via a diffusion-controlled quasi-reversible process was much more facile and easier than that occurred on GC electrode, which followed a diffusion-controlled three-dimensional instantaneous nucleation and growth. Scanning electron microscopy was used to observe that the deposit was dense and contained fine crystallites with average size of (80±4) nm. Energy dispersive spectrometer analysis showed that the obtained deposit was metallic nickel. X-ray diffraction spectroscopy indicated that (111) plane was the most preferred crystal orientation. The nickel deposit was luminous and bright, and had good adhesion with the CS substrate.

Key words: electrodeposition; bright nickel; nucleation mechanism; betaine·HCl; ethylene glycol